Class is created on RenderThread and we guarantee that it will be alive
until display compositor is destroyed, but UpdateOverlayBuffer is run
on GpuMain and can be posted while OverlayProcessor is alive but run
right after it's destroyed.

Manager can already outlive OverlayProcessor due to pending callbacks
and can be destroyed on both threads, so we can just extend life-time
for the duration of UpdateOverlayBuffer.

(cherry picked from commit 86a87b972fe850b48542bfc435a92c766e0a13c6)

Bug: 1515741
Change-Id: I80584596951b98ce99b9b4cbd4a3364278d1e967
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5176835
Commit-Queue: Vasiliy Telezhnikov <vasilyt@chromium.org>
Reviewed-by: Bo Liu <boliu@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1244651}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5199999
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/6099@{#1803}
Cr-Branched-From: e6ee4500f7d6549a9ac1354f8d056da49ef406be-refs/heads/main@{#1217362}